Title:Aegaeon (Saturn LIII), a G-ring object

Abstract: Aegaeon (Saturn LIII, S/2008 S1) is a small satellite of Saturn that orbits
within a bright arc of material near the inner edge of Saturn's G ring. This
object was observed in 21 images with Cassini's Narrow-Angle Camera between
June 15 (DOY 166), 2007 and February 20 (DOY 51), 2009. If Aegaeon has similar
surface scattering properties as other nearby small Saturnian satellites
(Pallene, Methone and Anthe), then its diameter is approximately 500 m. Orbit
models based on numerical integrations of the full equations of motion show
that Aegaeon's orbital motion is strongly influenced by multiple resonances
with Mimas. In particular, like the G-ring arc it inhabits, Aegaeon is trapped
in the 7:6 corotation eccentricity resonance with Mimas. Aegaeon, Anthe and
Methone therefore form a distinctive class of objects in the Saturn system:
small moons in co-rotation eccentricity resonances with Mimas associated with
arcs of debris. Comparisons among these different ring-arc systems reveal that
Aegaeon's orbit is closer to the exact resonance than Anthe's and Methone's
orbits are. This could indicate that Aegaeon has undergone significant orbital
evolution via its interactions with the other objects in its arc, which would
be consistent with the evidence that Aegaeon's mass is much smaller relative to
the total mass in its arc than Anthe's and Methone's masses are.